Thermostatic disk



0. A. CQLBY THERMOSTATIC DISK Dec. 27, 1927.

Filed July 1'7, 1926 I .1. E8 25 a6 WITNESSES:

Ora U. CO/b V ATTORNEY Patented Dec. 27, 1927.

UNITED STATES r 1,654,320 PATENT OFFICE.

ORA A. COLBY, QF MANSFIELD, OHIO, ASSIGNOR T0 WESTINGHOUSE ELECTRIC 8:

MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

THERMOSTATIC DISK.

Application filed July 17,

My invention relates to temperature-controldevices and particularly to snap-acting bimetallic disks.

An object of my invention is to provide a snap-acting bimetallic disk that shall embody means for reducing the strains set up in the disk by temperature changes.

In practicing my invention I provide a bimetallic disk having a plurality of openings therein which is initially deformed to cause it to operate with a nap action from one limiting position to another.

In the singlesheet of drawing,

Fig. 1 is a' view, in side elevation, of a thermostatic switch assembly comprising a device embodying my invention;

Fig. 2 is a top plan view thereof, and

Figs. 3 to 7 inclusive are top plan views of various modifications of a device embodying my invention.

Referring more particularly to Figs. 1

A and 2 of'the drawings, I have hereillustrated two co-operating metal disks 11 and 12 which are held in proper operative positions relatively to each other by a tubular metal member 13 located in a central opening in each of the plates 11 and 12, the ends of which are suitablyturned or spun over.

A disk 14 of electric-insulating material, such as mica, is located against the. outer face of the plate or disk 11 and a plurality of contact and 'terminal members 15, 16, 17, and 18 are insulatedly mounted upon the outer surface of the sheet or disk 14. The

terminal and contact members are of arcuate form and are positioned substantially as shown by the respective broken lines in Fig.

2 of the drawing.

The contact membels l6 and 17 are held by rivet members extending through, and insulated from, the plates 11 and 12. The

terminal members 15 and 18 are held by stud nut 27 is provided on the other -end of the 1926. Serial No. 123,217.

stud 25, whereby the position of the disk to the base of the device, may

.of. The locations of the respective bridging members 28 are su h that each member engages two spaced end portions of the fixed contact and terminal members hereinbefore described when the disk is in one of its limiting positions.

The bimetallic disk 24 is of the type disclosed and claimed in Patent No. 1,'148,24c0 issued to J. A. Spencer-and is'provided with a deformed or non-developable portion therein so that it is actuated from one of its two opposed limiting positions 'to'the other limiting position with a sna action. It is possible to cause thecontactridgin members 28 to engage the fixed contact an terminal members with a predetermined pressure to thereby permit of, an electric current flowing through the device without heating of the'contact, terminal and bridging members. When the temperature of the device has reached a predetermined temperature the peripher of the disk 24 is caused to move away rom the base, whereby the contact-bridging members are disen gaged from the fixed contact members, and a circuit therethrough is interrupted. In order to prevent any turning movement of the loosely mounted disk 24 on its support,

a pin 29 is provided in the base.- member which extends through an opening'in the disk, the result being that the contact-bridging members are maintained in proper operative alinement with the ends of the fixed contact members and in substantially the positions shown in Fig. 2 of the drawings.

A mathematical analysis of the strains set-up in a disk of this kind tends to show i that these strains are relatively high and may, in time, cause trouble because of the fatigue of the-metals employed in the bimetallic disk. I have found that the provision of a plurality of openings in the disk tends to reduce the strains in the disk .wit-hout apparently having any effect upon ing a plurality of circular openings 32 there-. in which are symmetrically spaced peripherally of the disk. The opening 33 is the one provided for the pin 29, and the openings 34 are the ones provided for receiving the mounting means of the contact-bridging members 28. 1

Fig. 4 illustrates a bimetallic disk 35 having a plurality of symmetrically spaced radially extending slots 36 therein, the other parts of the device being as herein before described in connection with Figure 3.

Fig. 5 illustrates a bimetallic disk 37 having a plurality of elongated openings 38 therein, the outer portions thereof being wider than the inner portions thereof.

Fig. 6 illustrates a bimetallic disk 39 having a pluralityof symmetrically spaced triangular openings 41 therein.

-Fig. 7 illustrates a bimetallic disk 42 having a greater number of openings 43 therein than are provided in the disk 39, the openings 43. being of substantially triangular shape. The disks 37, 39 and 42 conforni'in, all other respects, to the description given above in regard to disk 31.

In general, all the disks illustrated in Figs. 3 to 7, inclusive, may be described as embodying an inner or central portion and an outer peripheral portion connected by a plurality of; radially extending arms. Referring more particularly to Fig. 6, the disk 39 may be considered as comprising an inner portion 14 and an outer peripheral ortion 45 that are connected by three radia ly extending arms 46 which are integral with the inner and outer peripheral ortions. 1

W ile I have not made a mathematical analysisof the changes introduced'by the plurality of openings, I believe that the general result of providing such openings is to effect a material decrease in the strains setup in a disk of this kind, particularly during the time that it is moving from one position to another. My opinion is that the openings reduce particularly the tangentially extending strains in the disk of the material, so

that this strain is well within the limits permitted by the material employed in its construction. Actual devices'have shown that disks ofthis kind possess a high degree of snap action and such tests as have been made indicate that they will operate properly and for long eriods, of time under theconditions to w ich they are normally subjected. Various modifications maybe made. in the device embodying my invention without departing from the spirit and scope thereof, and} desire that only such limitations shall be placed thereon as are imposed by the prior art.

-I claim as my invention:

1. In a thermostatic disk having two opposed limitin positions and being actuated from one to t e other ofsaid positions with a snap action, said disk having spaced-apart apertures therein for reducing. the strains therein when deflecting from to the other.

opable portion therein, said diskbeing reciprocally self-actuable from one position to another with a. snap motion and means for 2. A bimetallic disk having a non-develreducing the strains in the disk during the time'that thediskis in motion, said means comprising a plurality of spaced-apart apertures located in the disk between the periphery and the center of said disk.

3. A thermally-actuable element comprising a bimetallic disk embodying a central portion, an outer peripheral portion and a plurality of spaced radially extending arms integral with the central and peripheral porone position- 

